The principles disclosed relate to an induction system for use on a motorcycle engine. More particularly, this disclosure concerns a tuned induction system for use on a V-twin motorcycle engine.
In general, internal combustion engines, whether for use in an automobile, motorcycle or other machinery, operate by drawing clean filtered air into a carburetor or a fuel-injected manifold. The air is mixed with fuel to form an air-fuel mixture or charge that is drawn into each cylinder of the engine and combusted. Combustion of the air-fuel charge produces mechanical horsepower. Horsepower is a significant factor in many consumers"" purchases of engines. Thus, many performance factors have been modified to increase engine volumetric efficiency and horsepower including structural variations of engine components and variations concerning the air-fuel charge.
In modifying engines to enhance performance, it is desirable to increase horsepower without increasing fuel emissions and fuel costs to operate the engine, or affecting engine durability. Therein, some design variations have been directed toward increasing horsepower by modifying the air intake component of the air-fuel charge. Although such design variations are commonly found in general internal combustion engines used in larger machinery applications, design variations of the air intake component of the air-fuel charge are limited for motorcycle applications.
As is well known, the extremely compact nature of a motorcycle gives rise to a number of design constraints. For instance, in modifying the air intake component of a motorcycle, placement of the induction system and charge forming devices is limited. This limitation is significant when designing an air intake or induction system that must fit within the small space between cylinder heads of a V-shaped or V-twin engine. Generally, V-twin engines have internally opposing air intake ports located on each of the V-angled front and rear cylinder heads. It is desirable to improve the induction systems for V-twin motorcycle engines to increase horsepower and torque without substantially increasing the V-angle and hence the overall size of the motorcycle engine.
One such improvement of an induction system involves using the advantages of a ram-air intake design. A number of arrangements have been proposed for providing ram air ducts on a motorcycle that supply air to the engine induction system. For example, arrangements have been provided wherein the cowling of the motorcycle itself forms an air duct for the induction system or wherein the frame is formed as an air duct for the induction system. None of these constructions, however, are feasible for use with a V-twin engine.
In general, improvement has been sought with respect to V-twin induction system designs to increase engine volumetric efficiency and horsepower without compromising fuel economy, emissions, or engine durability.
One aspect of the present invention relates to an air induction system having a first manifold body and a second manifold body. Each of the first and second manifold bodies is in fluid communication with respective first and second intake runners. The manifold bodies are configured to fit between the first and second cylinder heads of a V-twin engine.
Another aspect of the present invention relates to an air induction system having separate intake passages corresponding to a first and second cylinder head of a V-twin engine. The separate intake passages each include portions having integral flanges that couple the induction system to the cylinder heads.
These features of novelty and various other advantages, which characterize the invention, are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, its advantages, and the objects obtained by its use, reference should be made to the drawings which form a further part hereof, and to the accompanying descriptive matter, in which there is illustrated and described a preferred embodiment of the invention.